I am using the 3.0.0 kernel so that should not be a issue, have just upgraded mdadm on my box to 3.2.2 from 3.1.4 would i be right in thinking that to get from raid0 to raid5 i would first have to change from raid0 to raid4 and add the extra disk for parity, once i am at this level i would need a command to get the parity data striped over the raid5 and not in a single disk like raid4 or maybe there is a way to go from raid0 direct to raid5 by adding the extra disk and then having the parity data created and spread over the disks.... On 2 September 2011 13:49, NeilBrown <neilb@xxxxxxx> wrote: > On Fri, 2 Sep 2011 11:35:30 +0100 Michael Busby <michael.a.busby@xxxxxxxxx> > wrote: > >> Great, will test that in a bit >> >> will mdadm 3.2.2 support converting raid4 to raid5 >> >> "A RAID4 can change the number of devices or the size of individual >> devices. It cannot be converted to RAID5 yet (though that should be >> trivial to implement)" > > I guess the man page needs updating. You would need a reasonably recent > kernel... 2.6.30 or later. I guess that isn't so recent any more. > > NeilBrown > > >> >> On 2 September 2011 11:22, NeilBrown <neilb@xxxxxxx> wrote: >> > On Fri, 2 Sep 2011 10:12:32 +0100 Michael Busby <michael.a.busby@xxxxxxxxx> >> > wrote: >> > >> >> Thanks Neil >> >> >> >> Is there anyway back from raid0 to raid4 as i know once at raid0 i >> >> will no longer be able to add any disks, in theory i could change >> >> echo raid0 > /sys/block/md0/md/level,but this would require adding a >> >> missing disk to the raid4 at the same time, not sure how easy that >> >> would be todo >> >> >> > >> > Yes, you can switch from RAID0 to RAID4 in much the same way as you switch >> > from RAID4 to RAID0. >> > You can then freeze/add-disk/change-size/unfreeze/wait/switch-back-to-RAID0 >> > to add more devices. >> > >> > mdadm-3.2.2 should be able to do all this for you. i.e. you ask it to --grow >> > a RAID and --add some disks at the same time, and it will do all the required >> > magic. >> > >> > This hasn't been tested extensively, but should work in simple cases. >> > >> > Of course the more devices you have in a RAID0, the less reliability you have >> > - but e.g. as a cache for a tape backup system a large RAID0 is fine. >> > >> > NeilBrown >> > >> > >> > > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
